1. Field of the Invention
The present invention relates to a method of selecting a signal link in an exchange system, and more particularly to a method of transmitting a signal message when a link to transmit the signal message is selected in an exchange system.
2. Description of the Related Arts
Exchanges in communication systems require transmission links. In general, a transmission link is to be selected. The number of links between exchanges can be much greater than two, and may be variable. In such a case, signal links require special methods. Also, if a few unavailable links exist among several links, the methods should handle the unavailable links.
Among the exemplars of the contemporary practice is Obayashi et al. U.S. Pat. No. 5,566,358, Mobile Radio Communication Apparatus For Registering Location, Oct. 15, 1996) disclosing a mobile radio communication apparatus having a common channel detecting unit which judges whether or not a paging channel and an access channel which are assigned to one base station are commonly based on a predetermined parameter (CPA) which is transmitted from the base stations. If the CPA indicates a predetermined value establishing that the paging channel and the access channel are a common channel, then a memory stores information corresponding to that base station which transmits the strongest level of all the access channels received at an input of a receiver of the mobile radio communication apparatus. Ritter et al. U.S. Pat. No. 5,561,842, Mobile Radio Network, Oct. 1, 1996) endeavors to provide a ring-shaped network structure having a plurality of rings with range sections and a sector subdivision. The number of which corresponds to the number of cells positioned along a ring. Positioned in the center of a base station with antenna arranged at a raised location for illuminating all cells or for the reception from the individual cells respectively. The configuration uses a code division multiple access method. Mayrand et al. (U.S. Pat. No. 5,504,939, Communication Channel Selection In Cellular Radio Communication Systems, Apr. 2, 1996) uses a system for allocating communication channels within a cellular radio system in which each channel seizure request is assigned a call type based upon the capabilities of the mobile station, the nature of the call and the characteristics of the subscriber. A first algorithm is used to select a communication channel group for the call and a second algorithm is used to select an available communication channel from within the selected channel group. Patsiokas et al. (U.S. Pat. No. 5,396,648, Channel Acquisition Method And Apparatus For A Communication System, Mar. 7, 1995) attempts to construct a communication unit that transmits a communication channel request with the nearest base site making a communication channel grant or allocation. A base site receives the channel request signal, measures the signal strength level of the received signal, and if that level is above a threshold level, a communication channel is allocated to the requesting communication unit, thus establishing a communication link. From my study of the contemporary practice and of the art generally, I find that there is a need for an effective method and apparatus of transmitting a signal message when a link to transmit the signal message is selected in an exchange system that may use signal link selection values.